Static charge generating device



April 21, 1959 J. LARSEN ETAL 2,382,324

STATIC CHARGE GENERATINGDEVICE Filed Jan. 31, 1956 5 son r 3 h u 3 INVENTORY;

Jae/r Larsen George Nordqu/Isf ATTORNEYS United States Patent STATIC CHARGE GENERATING DEVICE Jack Larsen, Washington, D.C., and George Nordquist,

Bethesda, Md., assignors to the United States of America as represented by the Secretary of the Army Application January 31, 1956, Serial No. 563,169

3 Claims. (Cl. 102-702) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to generation of static electrical energy for ordnance devices by blowing dust past rubbing and collecting surfaces.

As is well known, when dust, such as talc or kaolin, is carried by an airstream over a metal surface the triboelectric efiect places opposite charges on the surface and the dust. This invention utilizes this phenomenon by placing a mixture of gas and dust at high pressure in a cartridge or bottle and expelling the mixture through a nozzle which acts as a rubbing surface. The charge on the dust is gathered in a collecting chamber and both charges-that acquired by the nozzle and that acquired by the collecting chamberare conducted to a capacitor for storage. Efilciency may be improved by using a series of nozzles and collecting chambers, electrically connected in parallel. Our generator is well adapted to providing electrical energy for use in ordnance fuzes.

The problems of generation of electrical energy for ordnance fuzes are unique as well as difiicult. Although the energy requirements are often rather low this energy must be available with great dependability almost instantaneously after long periods of storage. Besides being dependable and having long shelf life, a suitable power supply must be compact and rugged; it must be incorporated in a projectile and must withstand high acceleration or setback forces when the projectile is fired. Automatic activation of the power supply on setback is desirable. On the other hand, the power supply need have only a short active life and need not be rechargeable.

A principal object of the invention is to provide a rugged, compact, and economical source of electrical energy that can be quickly activated even after a long period of storage.

Another object of the invention is to provide such an energy source adapted to be incorporated in an ordnance fuze and to activate automatically in response to setback forces.

Further objects of the invention are to achieve the above in a cheap and simple manner with a device that is sturdy, reliable, and easy to manufacture.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from the following description and drawing, in which:

Fig. l is an axial section of an electrical generator in accordance with the invention taken on line 1-1 of Fig. 2. An associated energy-storage and detonator-firing circuit is shown schematically.

Fig. 2 is a cross section taken on line 2-2 of Fig. 1.

Fig. 3 is a cross section taken on line 3-3 of Fig. 1.

Fig. 4 is an enlarged view of the striker point.

In the figures the generator shown comprises a body constructed of an insulating material and having cylindrical bore 12 extending from shoulder 14 to open end 15. Extending axially along bore 12 are two diametri- 'ice cally opposed narrow grooves16 and 17 and one wide groove 18. Within narrow groove 16 is a narrow channel 20 and within wide groove 18 is a wide channel 22 both of conductive material. These channels 20 and 22 are respectively connected to terminals 24 and 26, which extend through the wall of body 10. Channel 20 is also electrically connected to tapered hole 28 by electrical conductor 29. In the bore 12 are alternately stacked large-apertured collector rings 30 and small-apertured rubbing plates 32. The small apertures 33 in the plates 32 act as nozzles. Between each plate and ring is an insulating washer 34. Each ring 30 has a wide protuberance 36 that fits snugly in channel 22. Each plate 32 has two diametrically opposed narrow protuberances 38 one of which fits snugly in channel 20 and the other of which fits in groove 17. A screen 40 is threaded into the open end 15 of bore 12 and electrically connected to channel 22.

A cartridge or bottle 42 is positioned with its neck 44 within the tapered hole 28. Bottle 42 is firmly held in place by resilient bail 46 which is attached to body 10 by pivots 48. Bottle 42 contains a mixture of gas, such as nitrogen, and dust, such as talc or kaolin, under high pressure and sealed by a diaphragm 54. Alternatively bottle 42 may contain a mixture of explosive material and dust, together with a suitable mechanically initiated firing device.

A striker 50 is positioned adjacent the bottle neck 44 and is adapted to either pierce the diaphragm 54 or initiate the firing device according to which is used.

This striker 50 has a pointed end 52 adapted to pierce the diaphragm or initiate the firing device. Around the point are slots 56 to allow the gas to pass through aperture 33. The striker 50 has a shaft 57 made of insulating material which extends through the several apertures 33, and out the end of the generator where it terminates with a weight 58. Helical compression spring 59 surrounds shaft 57 between screen 40 and weight 58.

The contemplated use of the generator is that it will be placed in an explosively charged ordnance projectile with terminals 24 and 26 connected to a capacitor 60. When the missile is fired the acceleration force acting on weight 58 overcomes the pressure of spring 59 and causes striker point 52 to pierce diaphragm 54, releasing the gasdust mixture. Or if the explosive charged cartridge is used the striker 50 may initiate the explosion and the release of dust. As the dust rubs past the neck 44 an opposite charge will appear on the neck and dust. The charge on neck 44 is drained to capacitor 60 through terminal 24. The charge on the dust is collected on ring 30 in the first collecting chamber and drained to the capacitor 60 through terminal 26. The air stream carries the dust through aperture 33 in plate 32 where it is again charged and into the second collecting chamber where the charge is again collected and drained. As many stages of charging and collecting are added as deemed feasible.

After the capacitor 60 is charged in the manner described and it is desired to explode the charge of the missile, switch 62 is closed by impact or other means known to the fuze art. This causes capacitor 60 to discharge through detonator 64 thereby activating it and subsequently exploding the charge of the missile.

It is contemplated that the dust be dyed red or any other brilliant color to give a visual indication on screen 40 that the generator has been activated.

It will be apparent that the embodiments described and shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

We claim:

1. An electrical generator comprising: a bottle filled with a mixture of compressed gas and dust, a diaphragm in the bottle adapted to 'be opened, a collector in front of the diaphragm, and means for conducting the charge that is triboelectrically generated on the bottle and collector to a storage "device.

2. An electrical generator comprising: a. bottle filled with a mixture of compressed gas and dust, a diaphragm in the bottle adapted to be opened, a rubbing plate-in front of the diaphragm, a collector in front of the rubbing plate, and conductors leading from the rubbing plate and collector so that when the diaphragm is opened and the dust blows out electrical charges produced on the rubbing plate and collector can be utilized.

3. In an ordnance fuze: a non-conducting'body containing coaxial large-apertured rings and small-apertured 5 2,492,493

plates alternately stacked therein and insulated from one another, a bottle containing .a mixture of .gas and dust under pressure, a striker positioned adjacent said bottle adapted to pierce the bottle in response to acceleration forces of firing, a capacitor, a conductor connecting all said plates to one side of said capacitor, a second conductor connecting all said rings to the other side of said capacitor, a detonator, and switch means for connecting said detonator across said capacitor.

References Cited in the 'file of this patent UNITED STATES PATENTS Simon June 11, 1935 Misson Dec. 27, 1949 

